3 files changed, 39 insertions, 0 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index 53a7385e1b4d..3ee1cbc89479 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -452,6 +452,39 @@ int scsi_dh_activate(struct request_queue *q)
 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 
 /*
+ * scsi_dh_set_params - set the parameters for the device as per the
+ *      string specified in params.
+ * @q - Request queue that is associated with the scsi_device for
+ *      which the parameters to be set.
+ * @params - parameters in the following format
+ *      "no_of_params\0param1\0param2\0param3\0...\0"
+ *      for example, string for 2 parameters with value 10 and 21
+ *      is specified as "2\010\021\0".
+ */
+int scsi_dh_set_params(struct request_queue *q, const char *params)
+{
+        int err = -SCSI_DH_NOSYS;
+        unsigned long flags;
+        struct scsi_device *sdev;
+        struct scsi_device_handler *scsi_dh = NULL;
+
+        spin_lock_irqsave(q->queue_lock, flags);
+        sdev = q->queuedata;
+        if (sdev && sdev->scsi_dh_data)
+                scsi_dh = sdev->scsi_dh_data->scsi_dh;
+        if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
+                err = 0;
+        spin_unlock_irqrestore(q->queue_lock, flags);
+
+        if (err)
+                return err;
+        err = scsi_dh->set_params(sdev, params);
+        put_device(&sdev->sdev_gendev);
+        return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_set_params);
+
+/*
  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
  *      the given name. FALSE(0) otherwise.
  * @name - name of the device handler.
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 1f3a4c8044c0..9af48cbf0036 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -187,6 +187,7 @@ struct scsi_device_handler {
         void (*detach)(struct scsi_device *);
         int (*activate)(struct scsi_device *);
         int (*prep_fn)(struct scsi_device *, struct request *);
+        int (*set_params)(struct scsi_device *, const char *);
 };
 
 struct scsi_dh_data {
diff --git a/include/scsi/scsi_dh.h b/include/scsi/scsi_dh.h
index 33efce20c26c..ff2407405b42 100644
--- a/include/scsi/scsi_dh.h
+++ b/include/scsi/scsi_dh.h
@@ -60,6 +60,7 @@ extern int scsi_dh_activate(struct request_queue *);
 extern int scsi_dh_handler_exist(const char *);
 extern int scsi_dh_attach(struct request_queue *, const char *);
 extern void scsi_dh_detach(struct request_queue *);
+extern int scsi_dh_set_params(struct request_queue *, const char *);
 #else
 static inline int scsi_dh_activate(struct request_queue *req)
 {
@@ -77,4 +78,8 @@ static inline void scsi_dh_detach(struct request_queue *q)
 {
         return;
 }
+static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
+{
+        return -SCSI_DH_NOSYS;
+}
 #endif